In many electronic electricity meters, communications with a meter microcomputer can be performed via an optical port or an option board connector. For example, in some known meters, an electrical connector is provided so that various option boards, such as a telephone modem communication board, may be electrically connected to the meter microcomputer. A central computer is often used to collect data, including billing information, from the meter, using the modem communication board. The data is available from the modem communication board in a predefined format (an ANSI defined protocol) on the communication channel which connects the option board connector to the meter microcomputer.
To reduce the number of nuisance and common event, e.g., power outage, calls, it is desirable to provide a modem unit, or board, which detects conditions within the meter and exchanges information with the central computer after the condition has existed for a pre-defined period of time. It also would be desirable to provide such a unit that would allow modification of the operation parameters. It would further be desirable to provide such a modem unit which can be easily and quickly coupled to a meter while allowing programming of a security password.
These and other objects may be attained by an electricity meter which, in one embodiment, includes a modem circuit, or unit, coupled to the meter microcomputer which exchanges information between the meter microcomputer and a central computer of the data source. Using the signals supplied by the meter microcomputer and the central computer, the modem unit can detect various conditions within the meter and determine the proper time for exchanging the information. In one embodiment, the modem unit includes a microcomputer having a plurality of timers.
In one aspect, the present invention is directed to allowing the programming of meter and modem unit passwords. Specifically, the meter and modem unit are placed into a password recovery state upon detecting closure of an external switch. Closure of the external switch simultaneously places the meter and the modem unit into password recovery states so that new passwords may be programmed into the meter and the modem unit by the central computer. Such a configuration avoids the time and expense associated with reprogramming the modem unit at the meter shop or having to send a specially trained individual to the meter site to perform the reprogramming.
In another aspect, the present invention is directed to limiting the number of calls initiated from the meter. More specifically, the modem unit microcomputer detects certain events and waits a pre-defined period of time before initiating the call to the central computer. In one form, after the modem unit detects a power outage indicator from the meter microcomputer, the modem unit waits a programmable period of time prior to an outage call being placed to the central computer. The modem unit microcomputer may be further configured so that in order to initiate the call to the central computer several conditions must occur within a pre-defined period of time. If all of the events do not occur in the specified period of time, the call will not be made to the central computer.
In yet another aspect, the present invention is directed to the modem unit answering calls from the central computer. More specifically, and in accordance with one form, the meter modem unit receives new program information from the central computer. The modem unit microcomputer program is stored in a non-volatile memory having two segments. A new program is stored in an inactive segment of the memory while the modem unit microcomputer executes a program from the active segment. If the programming is completed, the microcomputer changes the inactive segment to the active segment and executes the new program. However, if the programming is not completed, the modem unit microcomputer will continue to execute the program stored in the active segment. The two segments ensure that the meter will not be left in a partially programmed mode.
In still another aspect, the present invention is directed to utilizing multiple meters configured in a master slave arrangement. Information is exchanged between the meters and the central computer utilizing a single telephone line. More specifically, each meter includes a modem unit having a unique identification number. Prior to exchanging information from the central computer, an identification number is transferred to the meters. Each modem microcomputer determines whether the transferred identification number matches the identification number stored in its memory. If the numbers match, that modem unit exchanges information with the central computer. Those meters which do not match the transferred identification number wait and listen for the next transferred identification number to determine whether a match exists.
The above described modem unit detects multiple conditions and responds to those conditions at the proper pre-defined time to reduce the number of nuisance and common event calls. New operation parameters may also be transferred to the modem unit to allow modification of the condition and time parameters. The modem unit described above allows the password to be reprogrammed and the user does not have to pre-program the modem unit. As result, a new modem unit may be quickly installed in a meter.